This invention is in the field of carpet manufacture, and in particular relates to carpet and carpet tile prepared with a biocidal tuftlock precoat or fusion bonding adhesive.
Bacteria, fungi, viruses, algae and other microorganisms are always present in our environment. Such microorganisms are frequently an essential part of ecological systems, industrial processes, and healthy human and animal bodily functions, such as digestion. In other instances, however, microorganisms are highly undesirable as a cause of illness, odors, and damage or destruction of a wide variety of materials.
The species and numbers of microorganisms present in the environment are dependent on the nutrients and the moisture available for growth, as well as on the humidity and temperature. Nutrients for microorganisms generally abound in the normal environment.
A particularly good environment for the growth of microorganisms is found in carpet and carpet tile. Bacteria and fungi are deposited on the carpet through the everyday traffic of people and animals, food and beverages spilled on the carpet, and animal and infant waste. Further, airborne microorganisms carried in from outside or carried through the heating or cooling system can accumulate on carpet. Soil and moisture in carpet provide nutrients for the growth of the microbes. Moreover, certain bacteria are capable of remaining viable in a dormant state on carpet for long periods of time until they are provided adequate sustenance.
Organic materials used in the construction of carpet and carpet tile can be a source of nutrition for certain microorganisms. Carpet fibers are typically made from polyamides, such as nylon and wool, or from polyester, which are biodegradable. Tuftlock precoat or fusion bonding adhesives typically contain organic polymers in combination with fillers and other additives. Microbial digestion of these organic materials can result in the deterioration as well as the discoloration of the carpet over time. Further, the unhealthy accumulation of bacterial or fungal growth can create a foul odor.
It has proved difficult, however, to develop a microbiocidal composition that is effective in controlling the growth of the wide variety of unwanted microorganisms and is, at the same time, safe for use around human beings and animals. Another difficulty is the extreme variability of response of various microorganisms to conventional microbiocidal agents. Even within bacteria, Gram-negative and Gram-positive bacteria respond differently to antibiotics. Further, antibiotics that are effective against procaryotic organisms are usually ineffective against eucaryotic microorganisms such as fungi and yeasts.
U.S. patent application Ser. No. 047,561 entitled "Microbiocidal Composition and Method of Preparation" filed Apr. 27, 1987, by Robert H. McIntosh disclosed a broad spectrum, safe, biocidal composition having the following general formula: ##STR2## wherein R and R' are an alkyl, aryl, aralkyl or alkaryl group, one of R or R' can be H, X is a Group I metal ion, Group II metal ion, transition metal ion, or an organic ion such as an ammonium ion, and there is at least one free hydroxyl group. The biocide can be effectively incorporated into a large variety of substrates, such as detergents, coatings, plastics, wood and wood products.
U.S. Pat. No. 4,608,289 to McIntosh discloses a carpet which contains a dialkylalkoxyammonium dialkylphosphate in the backing coat of the carpet as a sanitizing agent against Gram Negative, Gram Positive and fungal organisms.
Antimicrobial agents now being marketed for use in carpet fibers include Dow Corning.TM. 5700 Antimicrobial Agent for textile fibers and OBPA (10,10-oxybisphenozarsine), marketed by Morton Thiokol, Inc. Dow Corning.TM. 5700 Antimicrobial Agent, marketed under the tradename SYLGARD, is a silicone quaternary amine of the general formula [CH.sub.3 (CH.sub.2).sub.17 N(CH.sub.3).sub.2 (CH.sub.2).sub.3 Si(OCH3).sub.3 ].sup.+ Cl.sup.-. It is applied to the carpet fiber and is activated in the presence of moisture. It does not kill microorganisms in the absence of moisture. Further, it is only active against Gram positive organisms. OBPA is highly toxic.
In addition to hygenic aspects of carpet construction, consideration must also be given to carpet durability and manufacturing versatility. The type of adhesive used for the tuftlock precoat or fusion bonding adhesive is important to these considerations.
The most widely used method of manufacture of fusion bonded carpet presently involves the use of a nonlatex PVC (polyvinyl chloride) plastisol formulation as the bonding adhesive. Typically, PVC plastisol is dispensed over a support layer to form an adhesive layer that penetrates into the support layer. The adhesive layer is then contacted with pile forming yarn. The PVC plastisol is cured, creating a product in which the yarn fibers are secured in the PVC layer and thereby bonded to the support layer. Increased strength may be obtained by bonding a secondary backing to the support layer.
Alternatively, pile yarn can be woven or tufted through a primary backing. The yarn is then adhered to the backing with a tuftlock precoat. This type of carpet, in which the yarn is mechanically as well as adhesively attached to the backing, is generally termed "woven" or "tufted" carpet. PVC plastisol formulations are commonly used as the polymeric base material in the tuftlock adhesive precoats.
In order to make a durable carpet in which the support layer does not peel away from the secondary backing, the adhesive which has permeated into the support layer must contact and bond with the material forming or adhering the secondary backing. The use of a nonlatex plasticized PVC as the yarn locking adhesive limits the variety of backing structures that may be applied to the carpet. This is true because nonlatex PVC plastisol does not bond strongly to common carpet backing materials such as bitumen, EVA (ethylene-vinylacetate), APP (atactic polypropylene), hot melts, urethanes, and SBR (styrene-butadiene). Furthermore, PVC plastisol is relatively expensive.
A carpet and carpet tile is needed for industry and the home that is not only resistant to the attack and growth of microorganisms, but that can be made with a variety of secondary adhesives and backings compatible with its assorted uses.
It is therefore an object of the present invention to provide carpet and carpet tile which is resistant to the growth of Gram negative bacteria, Gram positive bacteria, and fungi.
It is a further object of the present invention to provide carpet and carpet tile which maintains its resistance to microbial growth after cleaning or processing.
It is another object of the present invention to provide carpet and carpet tile which is rendered resistant to microbial growth without substantially adding to the cost of the product.
It is a still further object of the present invention to provide a method to prepare antimicrobial carpet and carpet tile.
It is yet another object of the present invention to provide a carpet and carpet tile which has a yarn locking adhesive which is compatible with a wide variety of adhesives and secondary backings.
It is a further object of the present invention to provide a carpet which is durable and economical.